groupmate
Groupmate is a noun used in English to refer to a person who is a member of the same group as another person. The term is most commonly applied in educational settings—such as a group project in a class—or in collaborative work contexts where a defined group shares tasks. A groupmate is distinguished from a classmate (someone in the same class regardless of grouping) and from a teammate (someone on the same team, which may be broader). The word is formed by combining "group" with "mate," with "mate" conveying a sense of companionship or partnership.
In use, "groupmate" emphasizes shared membership in a particular group rather than a formal role or friendship.